referencing application object without httpContext

I'm storing a list of logged on users in the sites application state object. There is also some user specific information stored in the cache, this info has a cacheItemRemovedCallback which closes the session on the database.

I'm trying to get the cacheItemRemovedCallback to also update the users table stored in the application state and have tried various ways which gives various errors:

1 - httpContext.current.application("usersTable").. do stuff..

..this compiles ok but gives an error ( NullReferenceException ) when cacheItemRemovedCallback fires.. I realised this is because since it's triggered by cacheItemRemovedCallback then there isn't an httpContext to reference and so can't access the application..
fair enough and to be expected!

2 - application("usersTable").. do stuff.. This fails to compile since 'Reference to a non-shared member requires an object reference'.. again, to be expected.

So my question is, is there a way I can access the application object without an httprequest to reference.

I've trawled google and various forums but no luck so any input would be great!